1. Field of the Invention
The present invention relates to a computer system, management computer and storage system, and storage area allocation amount controlling method, and more specifically to a method for mapping a virtual storage area to a real storage area according to frequency of usage by analyzing usage history.
2. Description of the Related Art
As information technique has been developed, data management is more and more demanded to be efficient. This is why a technique for using resources provided by a storage device from a host computer via a network has been developed. As storage has become more and more adaptive to a network, storage resources are desired to be shared effectively and speedily with dynamically allocating a storage resource to a logical storage unit. In such circumstances, a technique for dynamically allocating a storage area provided by a storage device to data according to an I/O request from a host computer is developed, and storage allocation of usage in case of the early start-up of storage operation or when capacity cannot be determined is realized.
[Patent Document 1] US2005/0055603 specification
A storage area allocation amount controlling method according to a conventional art allocates storage areas by dynamically mapping an address which is not mapped with a real storage area with the real storage area when it receives an I/O request from a host computer. The real storage area which is mapped at allocation has a fixed size. That is to say, capacity designated by the I/O request from a host computer is divided by a fixed size which was at the allocation of the real storage area.
In the case of a storage area allocation amount controlling method according to a conventional art, an allocated size of a real storage area is fixed. That brings about overhead occurs due to division by the fixed allocation size and initialization of the divided storage area when data whose size is over the fixed allocation size is written. Accordingly, I/O performance of the host computer is degraded.
The problem to be solved by the present invention is to provide a computer system, a management computer and a storage system, and a storage area allocation amount controlling method for improving I/O performance of the host computer.